Pressure gauge and pressure detecting circuit thereof

Abstract

The present invention provides a pressure detecting circuit, which is electrically connected to a coil to receive an induced electromotive force from the coil, including a movement detecting unit electrically connected to the coil to receive the induced electromotive force from the coil and find a distance of the movement of the magnetic device according to the induced electromotive force; and a converting unit electrically connected to the movement detecting unit to generate the voltage signal to indicate the distance. In addition, the present invention further provides a pressure gauge incorporated with the pressure detecting circuit.

What is claimed is: 
     
       1. A pressure gauge for measuring a pressure of a source, comprising:
 a case having a bore connecting the source; 
 a coil, which is made of a conductor, provided in the case; 
 a magnetic device movably received in the case; and 
 a pressure detecting circuit electrically connected to the coil; 
 wherein the magnetic device is moved by the pressure of the source that the coil generates an induced electromotive force, and the pressure detecting circuit receives the induced electromotive force to generate a voltage signal directly proportional to the induced electromotive force; 
 a flexible film provided on an inner side of the case to cover the bore that the pressure of the source expands the flexible film, and the flexible film moves the magnetic device; 
 a spring with opposite ends urging the case and the magnetic device, wherein the spring is compressed when the flexible film moves the magnetic device; 
 wherein the case includes a base and a lid engaging the base, and the base has the bore, and the lid has a chamber therein to receive the magnetic device and the spring therein; 
 wherein the lid has a main member with the chamber therein and a threaded hole communicated with the chamber, and a knob engaging the threaded hole to contact the spring that the magnetic device is adjustable by turning the knob; and 
 wherein a spring force of the spring for urging the magnetic device is adjustable by turning the knob. 
 
     
     
       2. The pressure gauge as defined in  claim 1 , wherein the pressure detecting circuit includes a movement detecting unit electrically connected to the coil to receive the induced electromotive force from the coil and find a distance of the movement of the magnetic device according to the induced electromotive force, and a converting unit electrically connected to the movement detecting unit to convert the distance into the voltage signal. 
     
     
       3. The pressure gauge as defined in  claim 2 , wherein the pressure detecting circuit further includes an adjusting unit electrically connected to the converting unit to adjust the voltage signal from the converting unit. 
     
     
       4. The pressure gauge as defined in  claim 3 , wherein the pressure detecting circuit further includes an output port electrically connected to the adjusting unit to transmit the voltage signal out.